This book was made possible by a decision of high US and Mexican government agencies to bring aliens with untreated leprosy from Mexico City and Guadalajara to the National Institutes of Health Clinical Center, in Bethesda, Md. One of the purposes of the investigation was to add to the existing knowledge of the natural history of leprosy.

Five patients were selected. All were under 30 years of age. All were males; four suffered from lepromatous leprosy and one from dimorphous leprosy. The entire admission consisted of two study periods; study period 1, for observation and medical tests, which lasted for two to three months, and study period 2, lasting from three to seven months, during which period specific therapy was given.

The contents are arranged in three main parts, namely, case summaries, a discussion of the findings, and tables. The patients were given the most thorough clinical and extensive laboratory